Elevated oxidative stress (OS) is widely accepted to be involved in the pathogenesis of Down syndrome (DS). However, the mechanisms underlying the elevation of OS in DS are poorly understood. Biometals, in particular copper and iron, play roles in OS. We therefore focused on biometals in the brain with DS. In this study, we analyzed the profile of elements, including biometals, in the brain of Ts1Cje mice, a widely used genetic model of DS. An inductively coupled plasma-mass spectrometry (ICP-MS)-based comparative metallomic/elementomic analysis of Ts1Cje mouse brain revealed a higher level of copper in the hippocampus and cerebral cortex, but not in the striatum, in comparison to wild-type littermates. The expression of the copper transporter CTR1, which is involved in the transport of copper into cells, was decreased in the ependymal cells of Ts1Cje mice, suggesting a decrease in the CTR1-mediated transport of copper into the ependymal cells, which excrete copper into the cerebrospinal fluid. To evaluate the pathological significance of the accumulation of copper in the brain of Ts1Cje mice, we examined the effects of a diet with a low copper content (LoCD) on the elevated lipid peroxidation, the accumulation of hyperphosphorylated tau, and some behavioral anomalies. Reducing the copper concentration in the brain by an LoCD restored the enhanced lipid peroxidation and phosphorylation of tau in the brain and reduced anxiety-like behavior, but not hyperactivity or impaired spatial leaning, in Ts1Cje mice. The findings highlight the reduction of accumulation of copper in the brain may be a novel therapeutic strategy for DS.
Keywords: Animal model; Anxiety; Copper; Down syndrome; Oxidative stress.
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